Hemodialysis International 2014; 18:374–383
Original Articles
Revisiting the association between altitude and mortality in dialysis patients Bryan B. SHAPIRO,1,2 Elani STREJA,1,3 Connie M. RHEE,1,4 Miklos Z. MOLNAR,1,5,6 Leeka KHEIFETS,3 Csaba P. KOVESDY,7,8 Joel D. KOPPLE,2,3 Kamyar KALANTAR-ZADEH1,3 1
Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, California, USA; 2The Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA and the David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; 3Departments of Community Health Sciences and Epidemiology, UCLA Fielding School of Public Health, Los Angeles, California, USA; 4Division of Nephrology, Brigham and Women’s Hospital, Boston, Massachusetts, USA; 5Department of Medicine, Division of Nephrology, University Health Network, Toronto, Ontario, Canada; 6University of Toronto, Toronto, Ontario, Canada; 7Division of Nephrology, Memphis Veterans Affairs Medical Center, Memphis, Tennessee, USA; 8Division of Nephrology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
Abstract It was recently reported that residential altitude is inversely associated with all-cause mortality among incident dialysis patients; however, no adjustment was made for key case-mix and laboratory variables. We re-examined this question in a contemporary patient database with comprehensive clinical and laboratory data. In a contemporary 8-year cohort of 144,892 maintenance dialysis patients from a large dialysis organization, we examined the relationship between residential altitude and all-cause mortality. Using data from the US Geological Survey, the average residential altitudes per approximately 43,000 US zip codes were compiled and linked to the residential zip codes of each patient. Mortality risks for these patients were estimated by Cox proportional hazard ratios. The study population’s mean ± standard deviation age was 61 ± 15 years. Forty-five percent of patients were women, and 57% of patients had diabetes. In fully adjusted analysis, those residing in the highest altitude strata (≥6000 ft) had a lower all-cause mortality risk in fully adjusted analyses: death hazard ratio: 0.92 (95% confidence interval, 0.86–0.99), as compared with patients in the reference group (
Original Articles
Revisiting the association between altitude and mortality in dialysis patients Bryan B. SHAPIRO,1,2 Elani STREJA,1,3 Connie M. RHEE,1,4 Miklos Z. MOLNAR,1,5,6 Leeka KHEIFETS,3 Csaba P. KOVESDY,7,8 Joel D. KOPPLE,2,3 Kamyar KALANTAR-ZADEH1,3 1
Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, California, USA; 2The Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA and the David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; 3Departments of Community Health Sciences and Epidemiology, UCLA Fielding School of Public Health, Los Angeles, California, USA; 4Division of Nephrology, Brigham and Women’s Hospital, Boston, Massachusetts, USA; 5Department of Medicine, Division of Nephrology, University Health Network, Toronto, Ontario, Canada; 6University of Toronto, Toronto, Ontario, Canada; 7Division of Nephrology, Memphis Veterans Affairs Medical Center, Memphis, Tennessee, USA; 8Division of Nephrology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
Abstract It was recently reported that residential altitude is inversely associated with all-cause mortality among incident dialysis patients; however, no adjustment was made for key case-mix and laboratory variables. We re-examined this question in a contemporary patient database with comprehensive clinical and laboratory data. In a contemporary 8-year cohort of 144,892 maintenance dialysis patients from a large dialysis organization, we examined the relationship between residential altitude and all-cause mortality. Using data from the US Geological Survey, the average residential altitudes per approximately 43,000 US zip codes were compiled and linked to the residential zip codes of each patient. Mortality risks for these patients were estimated by Cox proportional hazard ratios. The study population’s mean ± standard deviation age was 61 ± 15 years. Forty-five percent of patients were women, and 57% of patients had diabetes. In fully adjusted analysis, those residing in the highest altitude strata (≥6000 ft) had a lower all-cause mortality risk in fully adjusted analyses: death hazard ratio: 0.92 (95% confidence interval, 0.86–0.99), as compared with patients in the reference group (
